A: Peeling results when a wet substrate (e.g. the surface that has been painted) swells, causing the paint film to loosen, crack, and fall off. Amongst a variety of ways for water to seep under the paint film some are:
Worn-out or no caulking in joints, corners, and openings, allowing moisture to enter
Ice-filled or clogged gutters, using moisture build-up under the shingles
Interior moisture migrating through to the exterior walls
Painted surfaces that are too close to bare ground
Leaking Roofs
Painting a surface that is damp with rain, condensation, or dew